Heat loss and home insulation

 

Heat travels from hot areas to cooler areas. Therefore in cold weather when buildings are warmed up by heating systems and other 'incidental' gains such as appliances, machinery and even the people inside, the heat is continually being lost outside the environment as long as it is warmer inside than out.

 

The heat loss from a dwelling can be divided into two main categories:

 

Fabric heat loss heat loss as it is transmitted through the fabric of the building

Ventilation heat loss   heat loss through ventilation or draughts.

Standards of insulation in new housing are considerably higher than they are in older housing. However, properties built before current standards make up by far the largest proportion of the UK housing stock. In order to improve energy efficiency, reduce heating and hot water costs and to reduce CO2 emissions the fitting of insulation into existing housing stock is essential.

 

The following are types of insulation:

 

- Hot water insulation

- Roof insulation

- Wall insulation - both cavity and sold wall

- Draught proofing

- Floor insulation

- Double and secondary glazing.

 

Insulation slows down the rate at which the heat escapes, thereby reducing the need for heating.

 

A lack of insulation can have side effects:

 

- Cold water and window areas tend to make a room feel colder

- Warm air inside a room cools quickly and creates down draughts

- Warm air cools on cold surfaces, leading to condensation and draughts

 

Without loft insulation you could be losing as much as 15% of your heating costs through your roof. If you currently have no loft insulation and you install the recommended 270mm depth you could save around £155 per year on your heating bills and around 1 tonne of carbon dioxide (CO₂) per year. Insulating your loft is a simple and effective way to reduce your heating bills and you can even do it yourself.#

 

There are two main types of wall construction to be found in houses in the UK; cavity walls and solid walls. Most homes post 1930 will have some type of cavity wall with the pre 1930 more commonly solid wall. Often it can be distinguished by looking at the brick pattern as shown below.

 

Insulating a cavity wall involves filling the cavity between the inner and outer walls with insulating material and should only be carried out by a registered contractor. The contractor is normally responsible for deciding whether the walls are suitable for cavity fill, and is also responsible for making sure the work is completed properly.

 

Solid walls

Solid walls lose heat more quickly than cavity walls but because they are solid there is no easy way to insulate them. The two ways involve disruption to the existing building and are:

 

Internally -  by adding insulation lining to the inside of an external wall

Externally -  by adding insulation to the outer surface of the wall and then protecting it.

 

External wall insulation is more expensive than cavity wall insulation but it could save you around £380 a year on your energy bills and it could pay for itself in around 12 years. Internal wall insulation is cheaper than external wall insulation and you could save around £360 per year on your energy bill.

 

 

Figures for the amount of heat loss that can be accounted for as a result of draughts can range from 15 to 50% depending on the structure and exposure of the building.

 

There are several types of materials available from brushes, foams and sealants to strips and shaped rubber or plastic. Draught proofing is an easy, cost effective way to reduce heating bills. Most materials are available from DIY stores and should conform to the standard BS 7386.

 

Heat loss through floors is relatively slow compared to the other areas of an average house. Timber floors can be insulated by lifting the floorboards and laying mineral wool insulation supported by netting between the joists.

You can also use a regular tube sealant, such as silicon to fill gaps between floorboards and skirting boards to stop draughts. However, make sure that you don't block under-floor airbricks in your outside walls as floorboards will rot without adequate ventilation.

 

Double glazing systems tend to fall into two main categories:

 

- Ready made double glazed window units or replacement windows

- Secondary glazing where an extra pane is fitted to an existing window.

 

The addition of a second glass pane leads to trapped air which slows down the rate at which heat escapes outside whilst increasing the temperature of the internal pane. Double glazing saves you around £120 per year and also reduces noise levels and condensation levels of your house.

 

Insulating your hot water cylinder is one of the simplest and easiest ways to save energy and money saving you around £330 per year. Fitting a British Standard 'jacket' around your cylinder will cut heat loss by over 75%. If you already have a jacket fitted, check that it is at least 75mm thick.

 

More information can be found on the energy saving website

 

Heat project is a Home Loft & Cavity Wall Insulation Grants for home owners and private tenants in the UK. We provide grant assistance for your homes insulation needs, all insulation measures installed at affordable prices or in some cases for free.